Boring bar



July 14, 1931. SHARTWELL 1,814,921

BORING BAR Filed Sept. 30, 1926 2 Sheets-Sheet l Jwuentoz S. HARTWELL BORING BAR 2 Sheets-Sheet 2 Filed Sept. 30, 1926 Patented July 14, 1931 I FLOYD s. HAR'IWEiifl OFoLEiVhfAtTBj (iii to same Bite Appliea'ti'oh fiia septemter'so, 1926.- Serial no. 1551,741

invention is to rprovideiaboring bar .in which the slot for the .regeptionof the cutting elementis of a; crpssjseotional area to snuglyv receiye the putting,element-whereby the rear edge of; the. cuttingel'ement will-have efiecv zeqn c withitherear a let nth' q o to relieve the cutter holdingdevices of thruststrains I I A further and equally important obj ect f th n enti gi vtb p ev-idea ret ining an locking device for the cutting element having,

p e means? where y; the .samem y be adjusted to prop erllyposition and hold the :cut-J no ting elementinplace, thisufeature. avoiding, e necessityflof employing: taper locking Another; aim of the inventionxis to :provide -i a borin'gbar in whi'oh the arrangementand 2;) construction of parts:issnchthatthe mamb factnne andmaintenance of the-bar isgreatly simplified and: cheapened.

Other objects and advantages ,vi11 b ap-,

parent during-"the course of the following 2;) descr1pt1on-.- v

In the aceonipfanyingg drawings,gforniin a part of thls appllcation and inswhioh like? numerals: are ,e np'loyedto designate like par-tsthroughoutt-he same;

.35 V Figure, 1 is a fragmentary perspective of a boringbarcdnstrfloted-iH accordance with f Fi nre 6 is; a: rou fers ieotive' ilhfistr ai I h b p e 1 ngi'the 0'chi e and=. Qcetine h e karm ss);v

-ted el m n embodi dtin th ie e ti e; H Fi u 7- er p peered. to All st t 5 ing a cuttlng unit embodled ln'the lnventlon.

ofwthecuttingiunit maybe forced into elfeca ofthe locking screw 16.- Particular attention;

\ In the; dnawing's the numeral; 5 designates a hanjhaving GQDVBIltlQIlZDL-Ol: other; means-by Whichthe sa ne niay be attached to an OPE/IE; ating inechanisln. ;The forward portion of" thebar hasa slot 6 extending entirelyjthete- 55 throughfor the reception of a cuttingv unit; of any preferred design; More specifically the cutting unit in ay be in=thenature ofa block. havingseparat'ely adjustable blades? adapted to extend out throughopposite sides. of the banas in the case ofother too,lso,n th m ar' O the; wh n-hand, the; cutting;

unit- 7 maybe inathe nature of 'a single block the ends of Whi'ch are' sharpened-for engage v mentwith the Work; The; forward portion; of the cuttingunit 'iis providedvbetween-the. ends thereof with what inightbesaid to-be acani groove 8, the inner Wall of which; ex, tends at an angle to the 'plane of the cutting unit for engagement by'the cam'surfaceQrOf; 7 a locking and locating block 10. The cam sur -face 9 isformed hy reducing theforward portion of the block 10 as illustrated in Figqiirefi. I 1, i In carrying out the invention the rectjangnflan looking, and-locating block 1 0 is sllidably and non-rotatably received in-a squaredopeningfor socket "12in the body The inner portion of the opening 12 intersects the forward portionof the transverse opening 6 sothat the canrsu'rface'9 may enter the groove8 and have effective contact with the inner or bot; tom- WalL of. the same whereby the rear edge tive contact with the rear "WRlLOf the bar 5;

As illustrated in'Fig'ure 6 "the rear port-ion of the lookingand locating block 10 is pro vided with a; socket 1d toreceive the head 1-5;

is directe'd tothe fact that the socket 14;- is elongated in plan; viewand therefore freely receivesthehead 15 so that the head may be freely turned therein. The head 15 is, how-; ever, held Withinthesocket 15b3,". a pair of retaining pins 17 the ends of which are anchored to-the block-1O in such a-ina'nner that the intermediate portions otpins are posit tioned Within-the socket at opposite sides of;

the head 15 toengage the head. This p1jo= Vides a simple and reliable means to rotatably connect the locking screw 16 to the block 10 and at the same time to permit the block 10 to partake of a limited lateral movement without in any way disturbing the connection between the screw and the block.

Referring now to Figure 3, it will be seen that the locking screw 16 is carried by an internally and an externally threaded bushing 20 threaded into one side of the bar at about 90 degrees to the plane of the slot 6.

Preparatory to positioning the block 10 and associated elements in their proper places for the use of the bar, the rear terminal portion of the locking screw is threaded into the inner end of the bushing 20 and the block 10 is then positioned in the squared opening 12. After this, the bushing 20 is screwed into its socket in the bar, during which the screw 16 will be drawn into the bushing. The rear portion of the locking screw may have a hexagonal socket for the reception of a portion of an Allen wrench or it may have any other tool engaging means found desirable.

'After the cutting unit has been placed in the slot 6 and engaged by the locking and locating block 10 the oppositely positioned locating screws 30 may be advanced into engagement with opposite sides of the block 10 as suggested in Figure 2. The screws 30 may be turned in. or out to adjust the cutting unit within the slot 6 to cause the cutters at opposite sides of the bar to perform equal work as will be obvious to those skilled in the art. After the cutting unit has been adjusted the threaded openings which receive the screws 30 may be plugged with sealing wax or the like. In this connection it is noted that the rear portions of the locating screws 30 terminate a sufficient distance inwardly of the periphery of the bar to permit of the placing of sealing wax. The exposed portion of the threads in the openings will act as an anchoring means for the wax.

It is believed to be obvious that during the adjustment of the cutting unit 7 the sides of the block will be engaged with the more or less triangular end walls or shoulders 85 at the ends of the cam groove 8 whereby the turning of the screws 30 in the proper directions will result in the transverse adjustment of the cutting unit 7.

Particular attention is directed to Figure l which illustrates that the squared opening or socket 12 is sufliciently wider than the block 10 to provide for all reasonable adjustment of the cutting unit. In this connection it is also noted that the socket 14 is sufficiently longer than the lateral dimension of the head 15 to permit of lateral movement of the head 10 under the influence of the screws 30.

For subsequent adjustment of the locking unit- 7, sealing wax previously referred to, may be removed to afford access to the grooves or other tool engaging means at the rear ends of the screws 30.

Vith reference to the foregoing description taken in connection with the accompanying drawings it will be seen thatthe cutting unit may be expeditiously and securely locked in place without the aid of the taper locking screw ordinarily employed. It will be further seen that the thrust on the cutters is transmitted directly to the rear wall of the slot 6 so that the tendency of the cutting unit to shift when once adjusted is substantially reduced.

In use the cutting blocks can be taken to the tool room of a machine shop or other place of use and by placing them in a jig with a location lug engaging the cam groove 8 all blades may be set alike or substantially alike. However, if it is found when the'cutting block is again placed in the boring bar that the cutting blades do not indicate at true with each cutting tool the error may be corrected by adjustment of the screws 30 after which the screw holes are filled with melted wax. IVhen this has been done all cutting tools can then be set to size in the tool room by tool machinists or makers and the tools may be sent out into the shop for use by ma chine operators of limited intelligence. Therefore, the use of this invention permits manufacturers to secure accurate holes without being forced to employ highly skilled machinists to use the tools.

Having thus described the invention, what is claimed is:

1. A boring bar comprising a body having removable cutting unit, receiving and sustaining means therefor, said body being provided with an opening extending substantially transversely of the cutting unit and communicating laterally therewith, a looking and locating block in said opening, a locking screw, the block and screw having means for effecting a rotatable connection between the same and permitting movement of the block lengthwise of the cutting unit, a bushing threaded into said body and through which said screw is threaded, and locating means to engage said block to move the same laterally.

2. Aboring bar comprising a body having a slot and an opening communicating with the slot, a cutting unit in said slot and having a pair of shoulders, a locking and 1ocating block adapted to extend between said shouldersand engage said unit to secure the same in place, one of the contiguous portions of the block and unit between said shoulders being bevelled transversely of the axis of the unit to define a cam, means whereby said block may be advanced and retracted, and permitting movement of the block in the direction of the length of the slot, and means engaged with said block to move the same and the cutting unit transversely of the body.

3. A boring bar comprising a body having a slot extending entirely therethrough and having an opening communicating with the forward portion of the slot, a cutting unit in said slot and having a cam groove in the forward portion thereof and provided with a bottom wall extended at an angle to the plane of the cutting unit and having end walls, a locking and locating block in said opening and having a cam surface engaged with the bottom wall of said cam groove, a locking screw connected to said block, the block and screw having means whereby the two may be relatively adjusted in the direction of the length of the slot which is to say transversely of the opening, means engaged with said block to adjust the same and said unit transversely, and the relative lengths of said opening and block being such as to assure a bearing engagement of the block in said slot when in its various operative posi tions.

4. A boring bar comprising a body having a slot and an opening, said opening being squared, a cutting unit in said slot and having a cam groove and end walls, a block of rectangular formation in said squared opening and having a cam surface to extend into said c'am groove and engage the end walls of the same, a locking screw rotatably connected to said block, said connection permitting transverse movement of the block relatively of the screw, locating screws engaged with opposite sides of said block, and the relative lengths of said opening and block being such as to assure a bearing engagement of the block in said slot when in its various operative positions.

5. In a device of the class described, a body having a slot, a cutting unit therein, and the body being further provided with an opening extending substantially transversely of said slot and communicating therewith at one side, the combination of a locking and locating block working in said opening, the block and cutting unit having interengaging portions and the bottom of one of said portions being a cam surface, the block and cutting unit being thus connected for unitary movement in the direction of the length of the slot, the block having an elongated recess in its top surface and extending in the direction of the length of said slot, a screw threaded into said body and having a con stricted portion adjacent its inner end, said inner end of the screw being unthreaded and being received in said recess of the block, pins removably carried by the block and extending lengthwise of the recess to confine the unthreaded screw end therein, and means for adjusting the cutting unit and block in the direction of the length of the slot.

In testimony whereof I afiiX my signature.

FLOYD S. HARTWELL. 

